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Patient Information

Preventing Blood Clots

What are hospital associated blood clots?

A hospital-associated blood clot occurs in   patients when they are in hospital, and up to ninety days after a hospital admission.

There are two kinds:

  • Deep vein thrombosis (DVT): a DVT is a blood clot (also known as a thrombosis) that forms in a deep vein, most commonly in your leg or pelvis. It may cause no symptoms at all or cause swelling, redness and pain.
  • Pulmonary embolism (PE): If a clot becomes dislodged and passes through your blood vessels it can reach your lungs, this is called a PE. Symptoms  include coughing (with blood stained phlegm), chest pain and breathlessness. If left untreated a PE can lead to death.

Health professionals use the term venous thromboembolism (VTE), to cover both DVT and PE. 
If you develop any of these symptoms either in hospital or after you go home, please get medical advice immediately.                              

Are blood clots common?

Blood clots occur in the general population in about one in 1000 people every year. You may have heard about DVT in people who have been on an aeroplane, but you are much more likely to get a blood clot after going into hospital. In fact, about two thirds of all blood clots occur during or after a stay in hospital. Each patients risk is assessed on admission to hospital. If you are at risk, your doctor or nurse will talk with you about what will be done to offer you protection against clots.

Who is at risk?

Any unwell adult admitted to hospital is at risk. Other examples of factors that put people at greater risk include:

  • having an operation
  • a previous clot
  • a recent diagnosis of cancer
  • certain “sticky blood” conditions such as antiphospholipid syndrome or Factor V Leiden
  • being overweight
  • being immobile
  • oestrogen-containing contraceptives and hormone replacement.
  • significant injury or trauma
  • during and after pregnancy

What can be done to reduce my risk?


In hospital, you might be measured and fitted with anti-embolism stocking for your legs. You should be shown how to wear them and told to report any new pain or discomfort in your feet of legs. Your stockings will be removed for a short time everyday so that you can have a wash and check for any skin problems.

Inflatable sleeves

You may be asked to wear calf or foot pumps; special inflatable sleeves around your legs or feet while you are in bed or sat still in a chair. These will inflate  automatically and provide pressure at regular intervals, increasing blood flow out of your legs.

Blood thinners

Most patients at risk will be prescribed a small does of an anticoagulant (blood –thinner). These reduce the chance of having a blood clot by thinning your blood slightly. If you need to take these medicines when you leave hospital, you will be told how long to take them for. The blood thinner most often used is a type of heparin, which is given by injection. Please be aware that some “blood-thinners” are derived from animal origins. Please discuss this with your nurse or doctor if this is a concern to you. There may be reasons why some of the above are not suitable for you. To be effective, these methods of prevention must be used correctly and the course prescribed completed. If you have any questions or concerns, please ask your doctor or nurse.

What can I do to help myself?

If possible, before coming into hospital:

  • Talk to your doctor about contraceptive or hormone replacement therapy. Your doctor may consider stopping them in the  weeks before an operation and will provide advice on temporary use of other methods if your usual contraceptive is stopped.
  • Keep a healthy weight.
  • Do regular exercise

When in hospital:

  • Keep moving or walking and get out of bed as soon as you are able after an operation-ask your nurse or physiotherapist for more information.
  • Ask your doctor or nurse: “What is being done to reduce my risk of clots?”
  • Drink plenty of fluid to keep hydrated.

What happens when I go home?

Until you return to your usual level of activity, you may need to wear anti-embolism stockings after you go home. Your nurse will tell you how to put them on and what you should check your skin for. If you need to continue anticoagulation     injections at home, your nursing team will provide information and teach you how to do this. If you have any concerns make sure you speak to a nurse before you leave. It is important that you complete the prescribed course.

If you develop any sign or symptoms of a clot at home, seek medical advice immediately, either from your General Practitioner (GP) or your nearest Hospital A and E Department.

Useful sources of information

Please ask your doctor or nurse for more information.
NHS 111 - Offers health information and advice from specially trained nurse over the phone, 24 hours a day.

If you are diagnosed with a blood clot following discharge please inform us on 0121 685 4354 (there is an answer machine if you call out of hours).

The Royal Orthopaedic Hospital | T: 0121 685 4000 |